1. Field of the Invention
The present invention relates to a hard disk drive, and, more particularly, to a damping structure of a hard disk drive which is provided at a cover member to dampen an impact.
2. Description of the Related Art
As one of several possible information storage devices of a computer, a hard disk drive (HDD) is a device that is designed to reproduce/record data from/on a disk using a read/write head. In such a hard disk drive, the head moves to a desired position while flying above a recording surface of a rotating disk via an actuator and performs the reproducing/recording operations.
FIG. 1 is an exploded perspective view of a conventional hard disk drive, and FIG. 2 is a cross-sectional view of the hard disk drive shown in FIG. 1.
Referring to FIGS. 1 and 2, a hard disk drive includes a base member 11 and a cover member 12, a spindle motor 30 mounted on the base member 11, one or more data storage disks 20 installed in the spindle motor 30, and an actuator 40 to move a read/write head to a predetermined position of the disk 20.
The spindle motor 30 is supported by a flange 31, which is fixed to the base member 11. A bearing 37 is provided on an outer periphery of a shaft 32 of the spindle motor 30, allowing a hub 33 to rotate. The disk 20 is fitted into an outer periphery of the hub 33. Where a plurality of disks 20 are mounted into the outer periphery of the hub, a ring-shaped spacer 34 is installed on an outer periphery of the hub 33 in order to maintain gaps between the disks 20. A clamp 35 is coupled to an upper portion of the hub 33 in order to prevent the disks 20 from being released.
The actuator 40 includes a swing arm 44 that is pivotally mounted on a pivot 42 that is installed in the base member 11, a suspension 46 installed in one end portion of the swing arm 44 to elastically bias a slider 48 toward a surface of the disk 20, in which the head is mounted on the slider 48, and a voice coil motor (VCM) 50 to rotate the swing arm 44. The voice coil motor 50 is controlled by a servo control system. The voice coil motor 50 rotates the swing arm 44 in a direction based on Fleming's left hand rule by an interaction between current inputted to a VCM coil and magnetic field induced by a magnet. In other words, if the hard disk drive is powered on and the disk 20 starts to rotate, the voice coil motor 50 rotates the swing arm 44 such that the slider 48 on which the read/write head is mounted is moved over a recording surface of the disk 20. On the other hand, if the hard disk drive is powered off and the disk 20 is stopped, the voice coil motor 50 rotates the swing arm 44 such that the head escape from the disk 20.
The cover member 12 is assembled on an upper portion of the base member 11 through a plurality of coupling screws 18. A gasket 19 is interposed between the base member 11 and the cover member 12 in order to prevent dust or moisture from being introduced into the hard disk drive. The gasket 19 is generally formed of viscoelastic material, such as rubber, and attenuates vibration of the hard disk drive.
Screw insertion holes 14 and 15 are formed at the cover member 12, such that a shaft fixing screw 16 and a pivot fixing screw 17 may be respectively inserted thereinto. The shaft fixing screw 16 is coupled to the shaft 32 of the spindle motor 30 and the pivot fixing screw 17 is coupled to the pivot 42 of the actuator 40. The cover member 12 is generally formed of aluminium alloy using a die casting process to form the aluminium alloy. A thin stainless damping plate 60 is attached to the upper surface of the cover member 12 using a double-sided adhesive tape 61 in order to reduce noise of the hard disk drive.
According to the related art, a protrusion part 13 is formed along an edge of the cover member 12 in order to prevent scratches or other damage from occurring on a surface of the damping plate 60 during the assembling process of the hard disk drive. The protrusion part 13 is designed to extend higher than the upper surface of the damping plate 60 by a height “C”.
However, in the conventional hard disk drive constructed as above, a main object of the damping plate 60 is to reduce noise, unfortunately having a result in which an impact from an outside is not damped sufficiently. In more detail, if the hard disk drive falls down on a table while inclining toward the cover member 12, the protrusion part 13 of the cover member 12 collides with the table first of all. At this point, impact energy applied to the protrusion part 13 is directly transferred to the hard disk drive. Specifically, the impact energy is transferred to the spindle motor 30 through the cover member 12 and the shaft fixing screw 16, so that the bearing 37 of the spindle motor 30 may be damaged and the disk 20 is vibrated. Also, the impact energy is transferred to the slider 48 of the actuator 40 through the cover member 12 and the pivot fixing screw 17, and then, to the slider 48 through the actuator 40 installed in the base member 11. The transferred impact energy causes the slider 48 to be vibrated, such that the head mounted on the slider 48 collides with the surface of the disk 20. This phenomenon is called a head slap. The head slap damages the head and the recording surface of the disk 20, resulting in erroneous read/write operations of the hard disk drive.
Japanese Patent Laid-Open Publication No. 11-328946 discloses a damping plate, which is arranged spaced apart from an upper surface of a cover member by a predetermined interval. An object of this damping plate is to reduce noise. Since the damping plate is formed in a perfect flat shape, its damping characteristic is not satisfactory. Also, the damping plate is attached to the upper surface of the cover member using a double-sided tape. However, the double-sided tape is very thin, about 0.15 mm in thickness, such that impact absorption efficiency is low.